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Garner J, Skidmore S, Hadar J, Park H, Park K, Otte A, Jhon YK, Xu X, Qin B, Wang Y. Scanning Analysis of Sequential Semisolvent Vapor Impact To Study Naltrexone Release from Poly(lactide-co-glycolide) Microparticles. Mol Pharm 2022; 19:4286-4298. [PMID: 36166409 PMCID: PMC9643650 DOI: 10.1021/acs.molpharmaceut.2c00595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Poly(lactide-co-glycolide) (PLGA)-based microparticle formulations have been a mainstay of long-acting injectable drug delivery applications for decades. Despite a long history of use, tools and techniques to analyze and understand these formulations are still under development. Recently, a new characterization method was introduced known as the surface analysis after sequential semisolvent impact using sequential semisolvent vapors. The vapor-based technique is named, for convenience, surface analysis of (semisolvent) vapor impact (SAVI). In the SAVI method, discretely controlled quantities of selected organic semisolvents in the vapor phase were applied to PLGA microparticles to track particle morphological changes by laser scanning confocal microscopy. Subsequently, the morphological images were analyzed to calculate mean peak height (Sa), core height (Sk), kurtosis (Sku), dale void volume (Vvv), the density of peaks (Spd), maximum height (Hm), and the shape ratio (Rs). Here, the SAVI method was applied to naltrexone-loaded microparticles manufactured internally and Vivitrol, a commercial formulation. SAVI analysis of these microparticles indicated that the two primary mechanisms controlling the naltrexone release were the formation of discrete, self-crystallized portions of naltrexone within the PLGA structure and the degradation of PLGA chains through nucleophilic substitution. The relatively higher amounts of naltrexone crystals resulted in prolonged release than lower amounts of crystals. Data from gel permeation chromatography, differential scanning calorimetry, and in vitro release measurements all point to the importance of naltrexone crystal formation. This study highlights the utility of SAVI for gaining further insights into the microstructure of PLGA formulations and using SAVI data to support research, product development, and quality control applications for microparticle formulations of pharmaceuticals.
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Affiliation(s)
| | | | | | | | - Kinam Park
- Akina, Inc., West Lafayette, IN 47906, USA
- Purdue University, Biomedical Engineering and Pharmaceutics, West Lafayette, IN 47907, USA
| | - Andrew Otte
- Purdue University, Biomedical Engineering and Pharmaceutics, West Lafayette, IN 47907, USA
| | - Young Kuk Jhon
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Pharmaceutical Quality, Office of Lifecycle Drug Products, Silver Spring, MD 20993, USA
| | - Xiaoming Xu
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Pharmaceutical Quality, Office of Testing and Research, Silver Spring, MD 20993, USA
| | - Bin Qin
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Generic Drugs, Office of Research and Standards, Silver Spring, MD 20993, USA
| | - Yan Wang
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Generic Drugs, Office of Research and Standards, Silver Spring, MD 20993, USA
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Gonçalves KDO, Ribeiro L, Oliveira CMAD, Carvalho JF, Martins FT. New solvates of the drug naltrexone: protonation, conformation and interplay of synthons. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2018; 74:274-282. [PMID: 29504554 DOI: 10.1107/s2053229618001791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/29/2018] [Indexed: 11/10/2022]
Abstract
Naltrexone [systematic name: (4R,4aS,7aR,12bS)-3-cyclopropylmethyl-4a,9-dihydroxy-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one] is an important morphine-related drug used for combating alcoholism and opioid dependence. Of the eight crystal forms of naltrexone known thus far, only one exists in the neutral form and it crystallizes as a monohydrate. We have isolated the naltrexone free base as two new solvate forms, i.e. the ethyl acetate 0.33-solvate, C20H23NO4·0.33C4H8O2, (I), and the diethyl ether hemisolvate, C20H23NO4·0.5C4H10O, (II). While just one solvent molecule is present in the asymmetric unit of each solvate, there are three drug molecules (Z' = 3) in ethyl acetate solvate (I) and two (Z' = 2) in diethyl ether solvate (II). In (I), one of the three crystallographically independent drug molecules is present with its cyclopropyl group disordered over two sets of positions, as is the whole diethyl ether solvent molecule in (II). In all known forms, including the title forms, the naltrexone molecule exhibits the same conformation of the fused rings. The only conformational variability of naltrexone is in the cyclopropylmethyl group. Two conformations can be found around the bond connecting this group to the N-heterocycle, which is directly related to drug protonation. We have calculated, at the B3LYP/6-31G** level of theory, the minimum energy conformations of protonated and neutral naltrexone molecules for a chosen torsion angle about this bond. The lowest energy conformers depend on the protonation state and are in agreement with those found in the solid state. Within the cyclopropylmethyl group, the bond joining the methylene C atom to the cyclopropyl fragment also evidences conformational variability. In the literature, there are two well defined conformations around this bond. A third cyclopropyl conformation around this second bond is observed in the title solvates. Concerning the supramolecular features of the previously reported crystal structures, only one classical hydrogen bond between naltrexone molecules and one C(8) homosynthon is known, pointing to the robustness of this synthon and the difficulty in disrupting it. New R22(7) and C22(10) homosynthons are found in both (I) and (II), suggesting that their occurrence derives from crystallization of the neutral drug from nonpolar solvents.
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Affiliation(s)
| | - Leandro Ribeiro
- Institute of Chemistry, Federal University of Goiás, Goiânia, GO 74001-970, Brazil
| | | | | | - Felipe T Martins
- Institute of Chemistry, Federal University of Goiás, Goiânia, GO 74001-970, Brazil
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